When the sad news of Magenta Devine’s death came earlier this year, the tributes focused on two things: the striking image she always presented to camera (never seen without her trademark shades) and the fact that she was the undisputed champion of “yoof TV”. The late 80s and early 90s genre has long been derided by the snooty mainstream. But you only needed to see Devine in action to realise yoof TV is due a reappraisal.

Tough yet sweet, uncompromising yet relaxed: vintage footage of her inimitable style can be found on YouTube. Just watch her holding her own against a sneering John Lydon, interviewing him live from her pink padded caravan, refusing to be railroaded, listening and reacting and picking him up on his inconsistencies. It’s the 80s version of Parkie v Ali (“They’re morons, they’re cretins, I despise them,” Lydon says of the media. “Why do you do any interviews then?” interjects Devine.)

There was a pioneering spirit at the heart of yoof TV, which arrived in 1987 in the form of Network 7, an innovative live show aimed at the youth audience, which aired on Channel 4 for two hours on Sunday afternoons. An early title sequence reveal topics as varied as “pirate television, sexual offences … plastic surgery – and also live coverage of the marriage of an Italian couple” (which turned out to be a staged gay wedding, aired at the height of the Clause 28 debate). There were pieces on credit card fraud and hacking, demonstrated by masked men live as you watched; female boxing (“I’m appalled!” states a rare expert); even an interview with a man on death row, including a live viewers’ poll on whether they thought he deserved to die or not.

It was TV, but not as we knew it. There was non-linear storytelling, the pioneering use of infobars and blipverts, and a near-blanket ban on “experts”, with the presenting roles often assigned to the rookies reporting the stories. The whole experience trod the line between seat-of-the-pants excitement and ramshackle chaos.

“I always wanted to do a programme that felt like a channel within a channel – to be utterly subversive, to take over,” says Janet Street-Porter, the former LWT reporter/presenter who conceived Network 7 alongside LWT’s head of current affairs, Jane Hewland. Working with Keith MacMillan, the founder of The Chart Show, they devised a programme intended to disrupt, as apparent from the faux-glitchy title sequence.

“We wanted it to be as if the TV was suddenly hacked by another channel,” says Street-Porter. “Funnily enough, Tony James of the band Sigue Sigue Sputnik came up with [the phrase] ‘channel within a channel’ because he was totally into hacking and lifting anything in the music he was doing.’

The Tony James connection didn’t end there: his girlfriend – and Sigue Sigue Sputnik’s PR – was Magenta Devine. It was clear from the start that she was going to be the star of this bold new venture.

“We signed up as researchers,” recalls fellow presenter Tracey MacLeod. “I don’t think any of us knew we were going to be on screen, but we all knew Magenta would be … she was a natural star. She had such a fierce look, in both senses of the word. She was also a fiercely intelligent person. And kind.’

“Magenta was only ever Magenta,” adds Street-Porter. “She wasn’t really a career person; she was just her person.”

“That’s why I think losing Magenta hit people so hard,” continues MacLeod, “because she was someone who hadn’t really been seen on television before – someone who just didn’t seem to give a fuck. She just wasn’t interested in pleasing the audience.”

Few people could wrongfoot her, although a live interview with Dame Edna shows a rare moment of her missing a beat as she is chastised for wearing her dark glasses (“Eyes are very important!”). Yet that clip reveals something else that yoof TV deserves credit for – the sheer nonstop inventiveness of the production, with ambient noise to the fore (it’s filmed on a rooftop, construction work thudding in the background, while the interview eventually fades out when the voices swallowed up by the sound of a nearby fountain).

If that sounds as if it is veering into the world of pastiche, it was entirely unintended. “You didn’t know whether it was going to be a car crash or an amazing exposé,” says Charlie Parsons, a member of the production team who went on to create The Word, The Big Breakfast and Survivor. But it also meant for often brilliant television. They even bugged the Channel 4 boardroom to broadcast what they were saying about the show (“You just wouldn’t – you couldn’t – do that today,” says Parsons).

Other innovations included early coverage of MDMA, a live demonstration of how to make an acid house track – and a Dynasty-style “fashion soap” called Flesh + Blood, directed by the film-maker Joanna Hogg that anticipated shopping channels (“Janet had the idea that credits would come up for the clothes, like a magazine spread,” remembers MacLeod). Each episode would end with the crew, audience and guests congregating in the Docklands warehouse where it was shot, giving the impression that the party was going to continue. In the case of a walkabout interview with the Beastie Boys, with the band being as difficult as possible, the credits rolled as the band suggested it might be better to interview their dog instead.

The show was interspersed with global reportage strand reporting on stories from China to Africa. Meanwhile, Oliver James sat celebrities down on the psychiatrist’s chair to grill them for Room 113, while another regular slot, True or False, saw figures such as Jonathan Ross tell a Call My Bluff-style story, with viewers able to call in to vote on whether it was a lie or not. Many of the strands predicted the dominance of reality TV. “We did things like This Is Me, which was a little documentary about ‘my job, my life’ – and we did one about a trainee butcher cutting up a rabbit. There was outrage even then!” recalls Street-Porter.

Network 7’s production team were forced to live in a “Mad Max shanty town”. But Parsons believes it was the ban on experts that was Street-Porter’s greatest innovation. “The people that made the programme were also the people on screen – often regardless of whether they were talented at presenting or not!” he says. “That gave the programme an authenticity, because the presenters had actually researched it and knew what they were talking about.” This approach was, of course, also a question of resources, “making choices that made it look rougher and rawer, because we thought the content was more important than the smoothness. And that in fact added to the experience”.

That disarmingly raw approach was later brought to BBC2, when Street-Porter was in effect poached to expand her vision with DEF II, which allowed her to buy in US shows as well as develop her own – most notably Rough Guide, which Devine presented alongside Network 7’s Sankha Guha. “He could create that conspiratorial relationship with the viewer, which makes for a really great presenter,” recalls MacLeod. “But no one even realised this until the first live programme went out!”

The shorthand for the style of TV that Street-Porter helped to pioneer is often described as “magazine” format – a term that applies to much of today’s mainstream TV, from The One Show to Loose Women, where she now holds court. But it’s instructive to hear her own unique interpretation: “I was very interested in the fact that the approach to putting information across in newspapers was so linear, from A to B,” she says. “And you could apply that to everything – from reading a copy of the Guardian or the Times to watching Panorama. I was more interested in the approach taken by Time or Newsweek, where they boxed out information and would lead with a personal story because they wanted to get a bigger audience for a complicated story.’

‘The content was more important than smoothness’ …a collection of Network 7’s best bits.

Translated into the visual language of television, that meant the innovative use of graphics – much of them designed by Malcolm Garrett, famous for his record sleeve designs for Buzzcocks, Television and later Duran Duran. Because of the obvious pop music reference points, this approach was often accused of “dumbing down”. Street-Porter insists that the opposite was true. “We introduced the audience to things that were very complex in a way that they could go on and discover more for themselves,” she says. The thing is [to] place things in front of people and excite their interest … to tell people the facts they might need to know as the story went on.”

Often dismissed as a flash in the pan, Network 7 and DEF II left a legacy that can still be seen today. “I think what happened, fascinatingly, is a lot of the things we did filtered through into the mainstream,” says Street-Porter. “Certainly the presentation style did – you even see it in things like Panorama now.”

Macleod picks up the thread: “Rather than having a top-down version of journalism, where the presenter was this high-status figure telling you what to think, it was, ‘We’re going send these young people out and they’ll tell the story from the inside out’. That idea of the citizen journalist – and that plurality of voices was quite ahead of its time.”

They were also ahead of their time in terms of the racial, gender and sexual diversity of the cast. “We just put the smart people on,” says Street-Porter. “I had a very simple criteria, which meant I knew within an instant if they’d work or not: they all had to be brainy.”

For all its apparent faults, the show that was billed as “The future of television … today” can, 31 years later, teach the mainstream a lesson or two. “It’s taken a long time, but people are finally beginning to realise that, given the success of streaming, live TV is an important part of the future: to realise that events still constitute water-cooler discussion,” says Parsons. He splits yoof TV’s legacy into three strands: the breaking down of the “third wall” between presenter and audience; the introduction of reality TV as entertainment; and the embracing of live TV’s chaos. “Terrestrial television is still trying to find what ideas fit into those three things,” he concludes. “Rather incredibly, thanks to Janet and Jane and Keith, it all started there. That’s what the legacy is.”